Collect calls

What sounds like gibbon gibberish to the average person translates into species differentiation to a more educated and experienced ear

The middle of the Bornean jungle is not the ideal place to study for a Masters degree – unless your research subjects are among the world’s most elusive mammals.

Working around rapids and in dense jungle environments, UQ student Sunny Sanderson has been using a unique and clever method to examine the variations between different species of gibbon – their call.

Gibbons are medium-sized arboreal primates that live throughout the rainforests of South-East Asia in family groups.

“In the areas where I am working it is very difficult to access things, whether it is permits, food or resources,” Ms Sanderson said.

“So I decided to use vocalisations as an inexpensive, non-invasive means of sampling gibbon populations in Indonesian Borneo.

“Ideally, I would do a genetic study but that is quite often out of reach.”

While completing her Bachelor of Arts degree in 1999, Ms Sanderson received a UQ scholarship to study in Indonesia.

When there, she volunteered as a translator for an orangutan research station, which sparked her interest in primates and led her to return to UQ to complete a Bachelor of Science degree.

Ms Sanderson is currently studying a Master of Philosophy with the School of Integrative Biology under the supervision of Associate Professor Anne Goldizen.

She is looking at the variations in calls between gibbons in Borneo in order to determine where they are hybridising and, if so, the impact of this on the gibbon population.

“This research allows us to consider questions about speciation.

If these are truly different species then how is it that they can be interbreeding?” she said.

“It is believed the calls the gibbons make are a pre-mate isolating mechanism, so I am looking at the effect of altered call structures on hybrid groups.”

Every morning, the female gibbons make a “great call” as part of a duet with their mates to re-establish their pair bonds and their territory.

“The male and female will start whooping, then the female will do a few notes to silence the male before starting her “great call”, which begins with a few introductory notes,” Ms Sanderson said.

“Then she peaks and gets quite vigorous until she reaches her climax after which the male does a few notes. They go on like this for about half-an-hour every morning.”

The climax portion of the call is used to determine the species.

Different species of gibbon are separated geographically across South-East Asia. In Borneo, there are two species that have been hybridising, the Bornean Gibbon and the Agile Gibbon.

“The female Agile Gibbon will do between six and 15 notes over 20 seconds whereas the Bornean Gibbon does between 50 and 96 notes over a shorter period of time, so it is very easy to pick out the differences between hybrids and pure species,” she said.

Working in the geographical centre of Borneo, it takes between three and five days to get to the base camp using a variety of transportation including light planes, motorised boats and then small canoes.

The University of Cambridge runs the camp and Ms Sanderson is helped by four Indonesian field assistants.

She is one of only a few foreign researchers to have had the opportunity to work in the area.

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